Motor for tools.



Patented Dec. 5, |899.

P 1f .m Il

EI" /AW/ ment which it is used fo'r operating.

UniTnn FTnTns PATnNT @Trina CHESTER B. ALBREE, OF ALLEGHENY, PENNSYLVANIA.

MOTOR FOR TOOLS.

SPECIFICATION forming part of Letters Patent No.`638,490, dated December 5, 1899.

Application filed J' une l5, 1899.

To all whom it may concern:

Be it known that I, CHESTER B. ALBREE, of Allegheny, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Motors for Tools, of whichthe following is a full, clear, and exact description, reference being had to the accompanying drawings.

My invention relates to pneumatic tools, rock-drills, and other mechanism of the reciprocatory type, and is designed to provide simple means for permitting variable stroke of the reciprocating part, so that the piston will be reversed automatically even when it is stopped before the limit of its stroke. The facility which my apparatus possesses in this regard is of very great importance in the work to which such tools are ordinarily put.

Figure l of the accompanying drawings shows in vertical longitudinal section a motor constructed in accordance with myinvention and adapted to be operated with compressed air. Fig. 2 is a like view showing the parts in the position which they occupy when the piston is at the end of its back stroke. Fig. 3 is a View illustrating a modification. Fig. 4 is a vertical sectional view showing the application of my invention to a compound motor, and Fig. 5 is a like view showing that modification with the piston at the other end of its stroke.

In Fig. l, 2 represents the cylinder, having a cylinder-head 3 and a piston 4 of two diameters 4 4', which at its end has asocket T, designed to receive the tool or other instru- 5 is the inlet-port connected with a source of motive fluid-for example, compressed air. The piston has a hollow passage 6 extending through it, preferably cylindrical in form, and in that passage is a valve 7, which fits neatly therein, but can slide back and forth, as hereinafter explained. 8 8 are exhaust-ports leading from the hollow piston, and 9 9 are ports leading through the hollow piston, as shown.` Ihe valve 7 is formed with openings constituting ports l0, adapted to register with the exhaust-ports 8 when t-he valve isin the position shown in Fig. l and with ports ll, adapted to register with the ports 9 when the valve is in its other position. (Shown in Fig.

2.) 12 is a stop at the end of the hollow pas- Serial No. 720,600. (No model.)

sage of the piston, adapted to limit the back motion of the sliding valve.

The operation is as follows: The parts being in the position shown in Fig. l, motive fluid is admitted through the port 5, and, entering the cylinder at the smaller diameter of the piston, forces the piston back to the rear end of the cylinder, the air which is back of the piston being displaced through the passage 6, hollow valve 7, and exhaust-port 8 to the atmosphere. When the piston reaches the end of its back stroke and is stopped by engagement with the head 3, the valve 7 is caused by its inertia to move back into the position shown in Fig. 2, thus closing the exhaust-ports 8 and putting the ports 9 into communication with the interior of the hollow valve by way of the ports 1l, which then register therewith. Thereupon the air passes through the ports 9 l1, valve 7, and passage 6 to the cylinder back of the piston,thus tending to equalize the pressure therein with the pressure at the other end of the piston, and by reason of the differential area the piston is forced forward. When it reaches the end of its outstroke, or if for any reason, as isl very common in tools of this class, its motion should be checked by coming in contact with some obstacle before the end of its normal outstroke is reached, the valve 7 is caused by its inertia to move forward into the positionshown in Fig. l, and thereupon the rear end of the cylinder is cut off from the inlet and put into communication with the exhaust, and the compressed air, acting on the differential area of the piston, forces it back, the cycle of operations being thus continued. The automatic character of the work and the certainty with which the motor will reverse, although checked short of the full limit of its outstroke, renders the apparatus perfectly adapted to varied uses of the character above mentioned.

In Fig. 3 I show a modification of my invention in which the smaller diameter 4' of the piston is inclosed by a portion of the cylinder, and the exhaust instead of taking place directly from the hollow piston to the atmosphere passes into a space or recess 13, formed on the interior surface of the cylinder and communicating with the exhaust-ports 14.

The modification shown in Figs. 4 and 5 is IOO .designed to illust-rate the application of my invention to a compound motor which forms the subject of another application for Letters Patent tiled by me on June l5, 1899, wherein the motive fluid acts at high pressure to move the piston in one direction and then expansively at a lower pressure to move it in the opposite direction. In these views, Figs. 4 and 5, A represents the cylinder, having two portions A A', of different diameter, and Bis the inlet-port, opening into the larger portion A of the cylinder. D is the exhaust-port, communicating with an annular space C in the smaller diameter of the cylinder. The piston E has two portionsE and E, of different diameters, fitting, respectively, within the portions A A of the cylinder, and around the larger portion E is an annular recess of sufl'icient length to constitute a port which is always in communication with the inlet-port B in every position of the stroke of the piston. It will be understood that the shape of the parts B and F may be reversed, the port B being elongated and the port F being a single opening, and the same is true of the relations between the ports C and L, hereinafter described. Gisapassagewhichisformedlengthwise through the piston, having ports H, co1nm unicating with the ann ular port F,and ports L, communicating with the annular ports C, adapted by reason of the length of the ports C to be in communication therewith at every portion of the stroke of the piston. Ports J also lead from the passage G to the outer surface of the piston, at or near the shoulder K at the junction of the large and small diameters of the piston. The passage G is preferably cylindrical, and it contains a hollow sliding inertia-valve M,which lits neatly therein, but is free to slide back and forth. It has an exterior annular recess N, constituting a port of suhmicient length to register with and connect the ports H and J when the valve is at the outer end of the passage G, as shown in Fig. l. It has also a port O, leading from the interior to the exterior of the valve and adapted to register with the ports J when the valve is at the inner end of the passage G, as illustrated in Fig. 5. The valve has ports P leading from its interior to its exterior surface and adapted to register with ports L when the valve is at the outer end of the passage G, as shown in Fig. 4. The valve has also an exterior annular space Q, so situated that it does not register with any two of the ports L, J, or H at any position of the valve. Therefore it does not serve as a port, but its purpose is to contain coiled springs S S', the adjacent ends of which bear against a ring R, which is fixed to the interior of the passage G of the piston. The other ends of the springs bear against the valve at the ends of the annular space Q, and these springs are so related to each other in strength that normally they hold the valve in the position shown in Fig.4; but they are sufficiently flexible to allow the valve to be moved byinertia to the other end of its stroke in the manner explained below. f The piston has a socket or holder T,adapted to the tool which is intended to be used with it, and the cylinder has a suitable head V. At the end of the passage G is a stop U, adapted to limit the motion of the valve, and between the cylinder-head and the piston is a spring WV, which is adapted to return the piston automatically to the outer end of the stroke when the cylinder is disconnected from power in order to put the parts in position for starting, as explained below.

The operation is as follows: The parts being in the position shown in Fig. 4, to start the motor compressed airis admitted through the port B and thence passes, through the passage F and ports H, passage N, and ports J to the shoulder or differential area K on the piston and forces the piston to the rear end of the cylinder, the air contained in the rear portion of the cylinder being displaced, through the passage G, hollow valve M, ports P and L, and passage C, to the exhaust-port. lVhen the piston strikes the rear end of the cylinder, its motion is checked thereby, and the valve M by reason of its inertia moves back in the passage G until it is stopped by the stop U. The parts then are in the position shown in Fig. 2, in which the inlet-ports B and H are cut off from communication with the working space of the cylinder, and the space A2 of the cylinder at the shoulder K is put into communication with the rear of the cylinder by way of the ports J O and hollowvalve passage M, the exhaust-ports being cut oft from communication with the interior of the valve by the disconnection of the ports L and P. Thereupon the air Linder pressure which is contained in the space A2 ows to the rear end of the piston and by reason of its expansion forces the piston outward, the air-pressure per square inch decreasing as the motion of the piston continues and as the volume of the space in which the motive uid can expand increases. When the forward motion of the piston is checked, either by striking the end of the cylinder or by the striking of the tool against some object before the end of the normal stroke is reached, the valve M continues to move by reason of its inertia until it reaches the end of the passage G, whereupon the valve is brought again into the position shown in Fig. 4, another supply of motive fluid is admitted from the inlet B into the space A2, and any motive fluid remaining under pressure at the back end of the piston exhausts through the ports P, L, and D, the motion of the piston being thus reversed and the operation repeated, as above described.

In order to insure the starting of the piston, it is necessary that the passage N should be in register with the ports J and H and also that the piston should be at the outer end of its stroke. This is not always the po sition of the parts when the motive fluid lis cut off, and if the apparatus should come to IOO IIO

IZO

rest with the piston at the rear end of its stroke it must be moved to the other end in order to make it possible to start the apparatus. Great convenience is effected by doing this automatically.

The necessary automatic motion of the valve to its outer position is effected by the springs S S', which may be either in tension or compression and which, as above eX- plained, normally hold the Valve in the position of Fig. l. The spring W when the motive fluid is turned off presses the piston automatically to the outer end of its stroke, so that no matter at what portion of the stroke the piston may be stopped it will immediately assume the position required for starting. When the cylinder is vertical, 0r nearly so, with the piston extending downwardly, this spring is not necessary, for the automatic return of the piston will be effected by gravity.

The arrangement of the ports and passages shown in Figs. 4; and 5 may be varied, or more than one inertia-valve may be employed, without departure from the scope of my invention, an essential feature of which is the combination, with the other parts recited in the claims,of an inertia-valve tubularin form, and therefore balanced in its action, said tubular valve controlling a port affording communication between the spaces at the smaller and larger piston areas, respectively, and controlling also a separate exhaust-port. Forexample, the parts maybe arranged so that the motive fluid will act at high pressure to move the piston outwardly and will perform the backward stroke by expansion.

The springs controlling the valve M may be placed inside of the valve or at its ends or may be otherwise arranged to perform the function above explained.

` My invention may be modiiied in 4other respects, which will be suggested to those skilled in the art by the foregoing description.

I claim.-

l. Amotor having a piston with differential areas, a tubular valve carried by the piston and adapted to be moved by inertia when the motion of the piston is checked, a port affording communication between the spaces at the smaller and larger piston areas, said port being controlled by the tubular valve, and a separate exhaust-port also controlled by said valve; substantially as described.

2. A motor having a piston with differential areas, a tubular valve carried in a cavity therein and adapted to move from one end t0 the other of the cavity by inertia when the motion of the piston is checked, a port or ports in the body of the piston leading into the valve-cavity and communicating thereby with the portion of the cylinder adjacent to the larger piston area, said inertia-valve having a port adapted to register with said ports and to open and close the same alternately to control the exhaust of the motive fluid from the largenpiston-area chamber; substantially as described.

In testimony whereof I have hereunto set my hand.

CHESTER B. ALBREE.

Witnesses:

' THOMAS W. BAKEWELL,

M. SfMURPHY. 

